For subscriptions to feeds, it seems the only way to filter questions is by tags. Since meta-tags have been removed, filtering by tags does not allow to filter by meta-information.
This causes email subscriptions to easily be flooded with something like: 'the following 100 items were added to your ... feed', which motivates me only to unsubscribe, not to actually go through all of them. Subscriptions should allow to be notified less often based on individual preferences, and the tag system, now lacking meta-tags, is insufficient in that respect.
Search however has a rich interface to filter based on some meta-information, such as
[c++] closed:no score:0 answers:0 views:100+
Stack Overflow also has a toggle (unanswered / all questions) floating around on the questions search page, indicating someone thought this meta-data filter deserved special attention somehow.
Why not offer the ability to subscribe to questions feeds based on such filters?
Why not offer the same ability to define filters for the front-pages?
I know there must be user-scripts for this, but they are only a crutches helping individuals fanatics, not the masses.